The app comes with about 50 or so recipes, but also lets you create and edit your own. It has a nice selection of grains, hops, adjuncts, and yeast as well as a place to enter notes for the brew.
Also great is a "Schedule" function which tracks your batch and what should be done when (ie: transfer to secondary, bottle, serve, etc).
You enter each batch as you go. The app auto-calculates a number of things, including ABV% and calories. You also have the option to enter all of your information regarding OG, temp to ferment at, and duration.
Recent updates added the ability to email a recipe, and also added additional options for sorting recipes, including by color (which is also included when you create a batch).
I'd love to see calculations for amount of water to use and temps, but for now this is a great addition to my brewing space.
Now, during a brew, I can use my iPhone to make unit conversions, control my brewing tunes on the radio, and create and track my batches. I can also send texts and emails, make phone calls, and surf the web - all without sitting down in front of a computer.